WEYMOUTH — After losing to Dorchester in what was dubbed the “unofficial city championship” 11 days ago, and falling to campus-rival O’Bryant in overtime on Thanksgiving, it would have been easy to assume Madison Park had folded its tent for the season.

However, the Cardinals, who produced practically no offense in their last two games, sprang to life for an 18-6 victory against Bristol-Plymouth in the Division 4A semifinals Tuesday night.

In doing so, the Cardinals (8-4) not only fended off a team that upset the mighty Vincent Burton and Blue Hills on Thanksgiving, they also punched their ticket to their first Super Bowl since 1998.

It was the first playoff victory in school history, since its previous Super Bowl trips (1997 and 1998) came when the Boston City League had an automatic Super Bowl berth.

“I’m happy, I don’t know if I believe it right now though,” said senior tight end David Stewart, who scored on a 72-yard kick return to put his team ahead, 18-6, in the third quarter. “We just didn’t think about [the losses]; it was in the past. We focused on the future.”

Madison Park survived despite fumbling five times (and losing just one) in snowy conditions. B-P (5-7) lost two of its five fumbles, including one scooped up by senior Alexis Santiago on the first play of the game.

Santiago also collected a B-P fumble with 7:15 left in the half before he rushed for a 5-yard TD eight plays later to put his team ahead, 12-0, at the half.

“They fumbled a lot and we fumbled a lot, that’s all I can say,” B-P coach John Parris said before commenting on upsetting Blue Hills on Thanksgiving. “Thursday was a very emotional game, it was the game of our lives and we peaked too soon. We’re leaving with a smile though, we worked hard all season.”

Madison Park started strong in the second half but lost a fumble on the 47-yard line that led to B-P’s only score of the game, a 4-yard run by senior Adam Mota with 2:45 left in the third quarter.

On the ensuing kickoff, Stewart capped the Cardinals’ scoring with his 72-yard return.

“It was a real good cushion but we still had to work hard on defense and stop them from scoring,” Stewart said.

As it turned out, the kick return was not exactly the knockout punch. B-P punted on its next drive but junior Colin McGrath picked off Madison Park’s Hector Villar as time expired in the third quarter.

B-P’s ensuing 10-play drive stalled on the 31 after a key third-down stop. B-P got one final possession in the waning moments ,but any hopes of a comeback were crushed by Madison Park senior Kelvin Jones’s blindside sack on fourth down with a minute to play.

With that, the Cardinals looked ahead to Saturday when they have a shot at winning their first Super Bowl in school history. Madison Park will face Cathedral at 9 a.m. Saturday at Gillette Stadium.

“It will be historic, something to hang my hat on,” Santiago said. “We’ve never had one before, so it will be something really awesome to have our first Super Bowl.”